'Undead thorn disaster
This monster is one that just shouldn't be. There is no natural way for it to become an undead. There is no guideline or evolutionary methods for it to come to be. This monster came to be due to an extreme error in judgment and refusal to properly flow with what nature intends. The little intelligence it had was used to resist the natural flow of life to death and become an undead.
The thorns and vines that should have rotted in a high decay area were instead crystalized using the bones of other life affinity monsters that have already perished. The dark vines holding the bone white thorns are primarily made of skins, barks, and elastic decaying flesh. While it does not possess eyes, it uses smaller vines to still sense the flow of mana around and attack anything that has proper life mana within to extend the length of time it can use the body it has forced to exist.